Among car-laden sensors, there is such a sensor into the inside of which atmospheric air is introduced in order to prevent a space around the sensor from being subjected to a negative pressure to apply a load to a sensor, as a result of operations of the internal combustion engine.
There are some examples in the prior art which shows the connection between a gas sensor and a sensor controller or ECU, such as JP-07-111413B and JP-P2002-71640A. However, no consideration is given in these documents on the problem of intrusion of water into the inside of the sensor due to the negative pressure.
In the prior art there is a sensor in which atmospheric air is introduced into the sensor through a lead wire when the internal of the sensor is at a negative pressure caused by rapid or drastic change in the temperature. Also there is one example in the prior art in which a small bore is provided on a controller case so as to allow the lead wire and sensor to communicate with atmospheric air.